Totally second this. People, not only startup founders, underestimate how much data is already available from other companies (incumbents and new entrants) that operate in the same space. And although founders may think their products are unique, the majority of them are entering an existing market where many of the key insights about the business models are already known. You actually need to look for these existing insights, e.g. on the Internet or Facebook groups. It’s called “secondary research” (as opposed to primary research where you collect the data yourself through, e.g. experiments).